Polymicrobial community-acquired pneumonia requiring mechanical ventilation: A case series

Polymicrobial pneumonia may cause by combinations of respiratory viruses and bacteria in a host. Colonization by Streptococcus pneumoniae was associated with increased risk of Intensive Care Unit admission or death in the setting of influenza infection whereas the colonization by methicillin resistant Staphylococcus aureus coinfection was associated with severe disease and death in adults and children. The principal association of pathogens in community-acquired pneumonia (CAP) is bacteria and viral coinfection and accounts approximately on 39% of microbiological diagnosed cases of CAP. The emergency of influenza virus H1N1 in 2009 caused the first pandemic in more than 40 years. Several studies found bacterial coinfection in a quarter and one-half of influenza infections, the pathogens more frequent isolates were S. pneumoniae and S. aureus mixed pneumonia in all patient groups. The high rate of viral bacterial infection in CAP, should suggest the consideration of new treatments, also during influenza season, the rapid detection of influenza virus (A or B) may allow physician the effective use of neuraminidase inhibitors within 36-48 h of symptoms onset, reducing the complication of secondary bacterial infection. On the other hand, prevention of mixed infection by influenza and pneumococcal vaccine should be addressed. The differential clinical diagnosis between a viral and a bacterial CAP is not easy: No clinical signs or radiological findings help the clinician to suspicious the diagnosis. In this case series, we report five different cases of severe polymicrobial CAP: All of them required mechanical ventilation: Invasive the first two and noninvasive ventilation the last three cases.